1. Field of the Invention
The present invention relates to a size display system for an electronic camera which can obtain and record size information about an object to be photographed when taking a photograph, and can provide size as display as well as an object image for clarifying dimensions of the subject during photographing or reproduction.
To begin with, the term "electronic camera" used in this specification is defined as including electronic still cameras and video movie cameras (video cameras) such as VTRs integral with cameras. Also, the term "size information" is defined as including information necessary to calculate the size, such as in-focus information (information indicating an in-focus condition), zoom information (information indicating magnifications of a lens), distance information (distance up to an object), iris information (aperture value), and position information (position of a measured point in a frame or screen). Further, the term "scale pattern" is defined as including numerals, characters and figures such as scales, scale factors and unit symbols.
2. Prior Art
Some of TV monitors and the like have a system for displaying ID information as well as the image, when an object image photographed by an electronic still camera is reproduced. The ID information comprises identification for storage of field and frame, track number, date (year, month and day), time (hour, minute and second), user's area, etc.
That type prior electronic still camera capable of recording ID information incorporates only a circuit for recording the object image and the ID information.
Meanwhile, application fields of electronic still cameras have been remarkably widened in recent years. With such widespread use, there arises a demand, for example, to easily and accurately know the size and length of the photographed object image on the display screen.
However, conventional electronic still camera cannot meet such a demand because they only have the above-mentioned data display system at most.
At the present state, the purpose of accurately knowing the object size is achieved by simultaneously photographing, for example, a pencil or a cigarette which is suitable to compare the object in size.
Since the user's area in the ID information is freely available, it may be conceivable to utilize the user's area for that purpose. In practice, however, the user's area is only enough to indicate alphabet letters as many as about ten digits.
As an alternative for giving an indication during the photographing operation, there is also known a system of indicating distance information (Japanese Patent Laid-Open No. 1-309472).
This known system is to indicate the distance up to an object within an electronic viewfinder in the form of numerical value, but not to display dimensions and/or size of the object.
In the field of cameras using silver salt films, there has been proposed a scale-fitted camera for imprinting a scale in a print image on the film by LED, LCD or the like (Japanese Patent Laid-Open No. 63-155042).
However, that scale-fitted camera has no choice on whether or not to indicate the scale. In other words, the scale can no longer be erased once imprinted. Also, that scale-fitted camera does not include means (such as a circuit and a recording medium) for storing data necessary to indicate the scale. Moreover, the shape of the scale imprinted by LED, LCD or the like is fixedly determined with no possibility of, for example, rearranging the relationship between the scale and the print image for making it easier to see.
As mentioned above, no prior art has been found that can selectively display dimensions and/or length of a photographed object image, and enables easy and accurate comparison of the object image with a reference scale.
With a view of realizing a size display system for an electronic camera which can meet the above demand, it should be considered to prepare a region in which size information, a scale pattern or the like can be recorded without reducing the number of photograph frames available in a recording medium as far as possible.
For the purpose of more precisely knowing the size of an object, it is also required to increase accuracy of a scale which can be selectively inserted into an object image.
It is further desirable to easily and accurately know the distance between two arbitrary points on one or two objects to be measured, and sharply display those two measured points in the reproduced image of each object.
Meanwhile, in the case of conducting a presentation of commodities, there has been conventionally adopted a method of photographing an object by cameras using silver salt films and producing a paper print.
In this method of utilizing paper prints, a variety of techniques are employed to indicate dimensions of a printed object. For example, a scale is inserted into part of the photograph so that one may know the actual size of the object. Practically, a rule or any other well-known substance such as a cigarette case is photographed along with the object.
While the above method is adopted in the case of informing dimensions of commodities, a full-size enlargement of photographs is most effective to indicate the commodity dimensions.
However, the following various problems have been experienced in presenting a full-size indication by utilizing the silver salt photography.
(1) Problem of print size: At present, usual photographs are printed into the size of approximately 8 cm.times.12 cm, called service size. Use of this print size imposes limitations on what can be indicated by full-size photographs. It is of course possible to specify the print size other than the service size. But, use of the other print size is not practical because of being expensive and taking an extended print time.
(2) Problem of setting scale factor in printing: Even with photographs similarly called service size, they are different in the actual print size depending on types of printers used. Further, prints are enlarged by trimming part of the original negative film in many cases and the region subjected to the trimming is also different depending on types of printers used, making it difficult to evenly set a scale factor in the printing operation. (3) Problem in photographing: Usual cameras do not indicate what photographing scale factor (that is herein used to imply dimensions of a focused image relative to an actual object) is employed in the photographing operation. Only some macrolenses for single-lens reflex cameras bear photographing scale factors indicated thereon.